Rod Liddle, who has become the first blog writer to have a complaint upheld by the PCC. Photograph: John Lawrence / Rex Features

The former BBC Radio 4 Today editor Rod Liddle has been censured by the press watchdog for a blog on the Spectator website in which he incorrectly claimed that the "overwhelming majority" of violent crime in London was carried out by young African-Caribbean men.

It is the first time the Press Complaints Commission (PCC) has upheld a complaint against a newspaper or magazine over the content of a blog by a journalist.

In its ruling, the PCC said it recognised that blog posts were often intended to be provocative and prompt debate, but said it expected "the same standards in newspaper and magazine blogs that it would expect in comment pieces that appear in print editions".

The commission said the Spectator had failed to provide sufficient evidence to back up Liddle's claim that "the overwhelming majority of street crime, knife crime, gun crime, robbery and crimes of sexual violence in London is carried out by young men from the African-Caribbean community".

A number of readers took issue with the claim, published on the Spectator blog on 5 December last year. But the PCC said critical reader comments were not enough and the column had to be "corrected authoritatively online" by the magazine.

The PCC director, Stephen Abell, said: "This is a significant ruling because it shows that the PCC expects the same standards in newspaper and magazine blogs that it would expect in comment pieces that appear in print editions.

"There is plenty of room for robust opinions, views and commentary but statements of fact must still be substantiated if and when they are disputed. And if substantiation isn't possible, there should be proper correction by the newspaper or magazine in question."

The commission said the blog broke the clause on accuracy of the editors' code of practice.

"The first of an occasional series – those benefits of a multi-cultural Britain in full. Let me introduce you all to this human filth," wrote Liddle.

"It could be an anomaly, of course. But it isn't. The overwhelming majority of street crime, knife crime, gun crime, robbery and crimes of sexual violence in London is carried out by young men from the African-Caribbean community. Of course, in return, we have rap music, goat curry and a far more vibrant and diverse understanding of cultures which were once alien to us. For which, many thanks."

To back up Liddle's claim, the Spectator pointed to news stories in the Daily Mail and Sunday Times and to a BBC News report on London crime statistics.

The magazine said blogging was a "conversational medium" and the "piece as a whole had been written by the columnist and those who had commented". It had also published a separate blog post by another author who questioned Liddle's piece.

One person complained to the PCC, quoting statistics from the Ministry of Justice that suggested black people were not responsible for the "overwhelming majority" of violent crime in London.

"The commission recognised the magazine's argument that the nature of a blog post is often provocative and conducive to discussion. The blog in this case – which had been clearly attributed to the columnist – had certainly provoked considerable debate," said the PCC in its ruling, published today.

"However, the magazine had not been able to demonstrate that the 'overwhelming majority' of crime in all of the stated categories had been carried out by members of the African-Caribbean community," the commission added.

"It was difficult to argue that the sentence in question represented purely the columnist's opinion, which might be challenged. Instead, it was a statement of fact. As such, the commission believed that the onus was on the magazine to ensure that it was corrected authoritatively online. It could not rely merely on the carrying of critical reaction to the piece. The commission upheld the complaint under clause 1 of the code."

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